https://doi.org/10.1140/epjs/s11734-024-01186-3
Regular Article
Salinity stress-mediated lipid droplet production and liquid–liquid phase separation in Chlamydomonas reinhardtii
1
Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India
2
Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India
e
archanagayatri@yahoo.com
f
debjani.bagchi@gmail.com
Received:
26
January
2024
Accepted:
23
May
2024
Published online:
31
May
2024
High salt concentrations cause osmotic shock and oxidative imbalance in microalgal cells, thereby causing cell death. Innovative strategies are required to overcome the survival barrier and enhance the net productivity of bioenergy feedstock like lipids. In the current study, a gradient strategy for salt addition was employed to cultivate Chlamydomonas reinhardtii, and the effect of the step size was analyzed. The highest production of lipids was obtained at 150 mM NaCl salinity stress from gradient cultivation methods. The single stage produces smaller sized lipid droplets while the gradient induces the assembly of larger droplets. Lipid droplet (LD) assembly was found to lead to liquid–liquid phase separation (LLPS) of LDs from the cytosol. The characteristic of LLPS was analyzed with the help of various parameters such as spatial separation of LDs, LD number and size, and the area fraction occupied by LDs, and observed to be dependent on the mode of cultivation and age of the culture. The fluctuations in LD number and area are quantified by the parameter α (a function of the variance) and observed to be high in salinity stress conditions, implying heterogeneous response to stress. The pathways associated with lipid production were analyzed with the help of gene expression changes, which regulate the synthesis and breakdown of lipids, influencing LLPS. The combined action of autophagy, de novo lipid synthesis, and starch degradation together were found to enhance the lipid production in the gradient method.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjs/s11734-024-01186-3.
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